The use of organophosphorus compounds as a pesticide is widespread. This affects not only agricultural workers, but the entire population, e.g., organophosphorus compounds have been dispersed throughout the entire population in Florida and California in an attempt to control the Mediterranean Fruit Fly. This proposed research is to employ resealed erythrocytes containing DFPase for the prophylaxis and treatment of organophosphorus poisoning. The research program is directed toward the antagonism of organophosphorus poisoning by encapsulating DFPase into the red blood cell. Various DFPases will be prepared in large amounts and encapsulated into erythrocyte carrier cells to study its ability to prevent and antagonize the toxic effects of organophosphorus compounds which can be hydrolyzed by DFPase. These resealed erythrocytes containing this enzyme will be studied both in vitro and in vivo to determine the properties of these resealed erythrocytes containing DFPases. The use of organophosphorus compounds is increasing and has been of considerable concern to our agriculture industry. Because of the high frequency of exposure of agricultural farm workers, it is both an occupational and environmental problem. The toxic effects of organophosphorus compounds are well known, as one of their major toxic mechanisms is that they inhibit acetylcholinesterase, allowing acetylcholine to accumulate to toxic concentrations.